Natural and synthetic zeolitic materials of the molecular sieve type are known and are staple items of commerce. Crystalline zeolites are extremely well known in the art and have been the subject of much attention in both the patent and technical literature. These materials have been demonstrated to have catalytic properties for various types of hydrocarbon conversions.
Because of their unique molecular sieving characteristics, as well as their potentially acidic nature, zeolites are especially useful in hydrocarbon processing as absorbents, and, as catalysts, for cracking, reforming, isomerizing, and other hydrocarbon conversion reactions. Although many different crystalline aluminosilicates have been prepared and tested, the search continues for new zeolites which can be used in hydrocarbon and chemical processing.
An increasing number of zeolite structures have been made by synthetic methods. Each new structure holds out the possibility of enhanced process selectivity based upon the size of molecules which can move about in the pore system of the catalyst. Aside from the 3-dimensional lattice structure of the crystalline zeolite, elemental composition can be an important factor in the selectivity of catalyst. Catalytic performance may be related to the extent of framework substitution or the type of element which is substituted into the framework.
It is generally known that the structure and composition of zeolites may be varied by the synthetic use of readily available inorganic reagents. There are instances where pre-aged components or even crystalline inorganic materials including other zeolites may be used as reagents to vary the structure and composition of zeolites.
In work reported by Lowe et al. (Proc. 5th Int'l Zeol. Cond.) Naples, p. 85, the formation of "active" silicates was described as highly desirable in A, X and Y synthesis. In U.S. Pat. No. 4,676,958, it is shown that using a crystalline silicate, magadiite, can be beneficial in producing high silica zeolites from a variety of organo-cations or template molecules.
In some zeolite syntheses, one zeolite structure can be found to be a transient phase en route to the formation of the more favorable, but slower crystallizing product. For example, in a synthesis of ZSM-4, Y-type zeolite can be a reaction precursor (see J. Catal. 1979 59 263). A similar result was found for the preparation of zeolite SSZ-13 under high OH.sup.- conditions (Zeolites 8 166, 1988). U.S. Pat. No. 4,910,006 discloses that using a known zeolite as a reactant in the synthesis of a novel zeolite provides benefits in terms of the reaction rate for the formation of a novel zeolite and the purity of the novel zeolite.